In certain industrial operations it is known to collect liquid at an elevated location and return it by means of a barometric dropleg conduit means to a point of use located some distance below the elevated location. An example of one such operation is in papermaking apparatus involving a cleaner system wherein a portion of cleaned, deaerated papermaking stock is conveyed from an elevated chamber maintained under vacuum back to a wire pit or silo or alternatively to the suction side of a pump drawing dilution water from the silo for delivery of such dilution water to a cleaning stage operation. U.S. Pat. Nos. 3,206,917 and 3,770,315 are exemplary of such apparatus, system and particular liquid return operation except that the point of use for liquid return disclosed in said patent is to the suction side of a cleaning stage feed pump rather than to the wire pit.
It has been found that where papermaking suspension overflow from the elevated stock receiver which overflow passes over a weir in the stock receiver, is conveyed back to the wire pit or pump suction side in a barometric dropleg conduit, undesirable vibration, pulsation, noise and the like may be produced in the dropleg conduit which conditions could be detrimental to the achievement of optimized operating performance of the overall papermaking system.